Supporting and current supplying means for consumable electrodes in electric furnaces



Oct. 9, 1962 R. J. GARMY 3,057,935

SUPPORTING AND CURRENT SUPPLYING MEANS FOR CONSUMABLE ELECTRODES INELECTRIC FURNACES Original Filed Nov. 22, 1957 9 Sheets-Sheet 1 l l I 13 15m 1 i w! i l l- T Ii! [A l 1 a men/v.5" '1 QQQHHEHNHQHQ'NHQHW dCEHNE 4 G O O INVENTOR.

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Oct. 9, 1962 R. J. GARMY 3,057,935

SUPPORTING AND CURRENT SUPPLYING MEANS FOR CONSUMABLE ELECTRODES INELECTRIC FURNACES Original Filed Nov. 22, 1957 9 Sheets-Sheet 2 Oct. 9,1962 R. J. GARMY 3,057,935 SUPPORTING AND CURRENT SUPPLYING MEANS FORCONSUMABLE ELECTRODES IN ELECTRIC FURNACES Original Filed Nov. 22. 19579 Sheets-Sheet 3 INVENTOR.

90 4 05097 I 6AA MV Arrow/E) 9, 1962 R. J. GARMY 3,057,935

su RTING AND CURRENT SUPPLY MEANS FOR (:0 MABLE ELE CTRODES IN ELEC CFURNACES Original Filed Nov. 22. 1957 9 Sheets-Sheet 4 Film i! INVENTOR.FOBCWTJ GAE/WV H7 7 O/P/VE V O 1962 R. J. GARMY 3,057,935

SUPPORTING AND CURRENT SUPPLYING MEANS FOR CONSUMABLE ELECTRODES INELECTRIC FURNACES Original Filed Nov. 22, 1957 9 Sheets-Sheet 5INVENTOR. 05597 J 64/614) Oct. 9, 1962 R. J. GARMY 3,057,935

SUPPORTING AND CURRENT SUPPLYING MEANS FOR CONSUMABLE ELECTRODES INELECTRIC FURNACES Original Filed Nov. 22. 1957 9 Sheets-Sheet 6 1NVENTOR faamr jA/P/W) Oct. 9, 1962 R. J. GARMY 3,057,935

SUPPORTING AND CURRENT SUPPLYING MEANS FOR CONSUMABLE ELECTRODES INELECTRIC FURNACES Original Filed Nov. 22. 1957 9 Sheets-Sheet 7 Ti: 11.W

I N VEN TOR. K BE/Q7 J @sve/wy Oct. 9, 1962 R. J. GARMY 3,057,935

SUPPORTING AND CURRENT SUPP NG M S FOR CONSUMABLE ELECTRODES IN EL RICNACES Original Filed Nov. 22. 1957 9 Sheets-Sheet 9 i INVENTOR.

Row/e7 J 6mm y United States Patent 3,057,935 SUPPORTING AND CUNTsurrhrnso MEAN FOR CONSUMABLE ELECTRUDES EN ELECTRIC FURNACES Robert J.Garlny, Canton, @hio, assignor to Republic Steel Corporation, Cleveland,Ohio, in corporation of New Jersey 14 Claims. (Cl. Iii-14) This is adivision of my copending application for US. Letters Patent, Serial No.698,256, filed November 22., 1957, now Patent Number 2,973,452, issuedFebruary 28, 1961, entitled Electric Furnace Utilizing ConsumableElectrodes and Method of Operating Same.

This invention relates to electric furnaces and particularly to furnacesfor producing metallic ingots of high purity. The furnace describedherein was designed especially for use with and has successfully beenused with metals such as titanium, zirconium and the like, which aredifficult to melt because of their high melting points and also becauseof their high chemical activity at their melting points. This furnacehas also been successfully used with other metals, e.g., steel, where aningot of high purity was desired.

A problem of particular difliculty in connection with furnaces for usein the melting of titanium and the like is the problem of safety withrespect to the persons controlling the operation of the furnace andloading and unloading it. The extremely high operating temperaturesinvolved, in the neighborhood of 3140 F. (the melting point of titanium)and the great chemical activity of metals such as titanium and zirconiumat their melting points make the probability of an explosion extremelyhigh if oxygen, air or water is allowed to leak into the furnace.Furthermore, if the structural parts of the furnace (which are commonlymade of other metals having lower melting points) become overheated,those parts are likely to be destroyed, with resultant contact betweenthe molten titanium and air or water.

Another difficult problem in connection with such furnaces is thedifficulty of loading them. The furnace described herein is fed withconsumable electrodes formed of titanium and/or other metal to betreated. For example, these electrodes may be compressed from titaniumsponge and/or scrap by the method and apparatus described in thecopending application of Thomas A. Sindelar, Serial No. 571,810, filedMarch 15, 1956, now Patent Number 2,925,619, issued February 23, 1960,entitled Consumable Electrode Billets and Method and Apparatus forMaking the Same. These electrodes are melted in the furnace by means ofan arc so that the electrode itself must carry heavy electrical current.In loading such an electrode into the furnace, it is necessary not onlyto connect it physically to a supporting structure, but also to connectit electrically to a power supply structure. Furthermore, the supportingstructure must be adapted to move or feed the electrode to the arc.Since large currents are involved, the electrical connection of suchelectrodes has in the past been a rather time consuming operation.

Although continuously fed furnaces have been suggested, so far as isknown, all commercially successful furnaces up to the present, includingthe furnace disclosed herein, have been batch furnaces, using electrodesof finite length.

down after each electrode is consumed for the insertion of a newelectrode, the size of ingot which can be pro- 3,057,935 Patented Get.9, 1962 duced is limited by the size of electrode which can be fed.Consequently, increasingly larger electrodes are being used to producethe larger ingots, and th problem of supporting such electrodes isbecoming increasingly difficult.

An object of the present invention is to provide improved apparatus forloading a consumable electrode into a furnace of the type described andfor making electrical contact to such an electrode.

Another object of the invention is to provide improved mechanism forsupporting an electrode in the furnace and for feeding it to the arc.

The foregoing and other objects of the invention are attained, in thefurnace described herein.

The furnace includes a crucible mounted on a truck for horizontalmovement along a set of rails. The crucible is supported on the truck bymeans of a set of jacks so that it may be raised and lowered on thetruck. When in its operating position, the crucible is raised on thetruck so that its upper end sealingly engages the periphery of anopening in the bottom of a furnace shell.

Mounted on the upper end of the shell is a vertically elongatedelectrode receiving casing or tube. The electrode supporting mechanismis located above the elec trode receiving tube and includes a power tubewhich extends through a seal in a cover at the top end of the electrodereceiving tube and is vertically slidable in that seal.

The mechanism for supporting and feeding the electrode includes a clampfor engaging an end of the electrode. The clamp serves both as a supportand as a means for conducting electric current to the electrode. Theclamp is removably fastened to a contact plate located at the bottom endof the power tube which extends upwardly through the cover of theelectrode receiving tube. The upper end of the power tube is attached bymeans of terminals and cables to a power supply. The power tube hangsfrom a crosshead which moves on two vertically extending lead screws.The lead screws hang from a crossbar mounted on two vertical masts. Thelead screws are driven concurrently by a motor and suitable connectinggears and shafts. The entire supporting mechanism, including the motor,the masts, the crossbar, the crosshead, and the power tube and relatedparts are mounted on a carriage which is movable horizontally andlocated just below the level of the upper end of the electrode receivingtube. This carriage may be moved between an operating position in whichthe power tube is aligned vertically with the electrode receiving tubeand a loading and unloading position in which the power tube and all thesupporting mechanism are displaced horizontally from above the electrodereceiving tube to permit the insertion of a new electrode by means of acrane or the like.

Each electrode clamp is provided with means, for example, horizontalholes, through which rods may be inserted, to support it temporarily onthe top of the electrode tube. When loading a new electrode, the coveris removed from the electrode receiving tube and is lifted upwardly uponengagement by the contact plate carried at the lower end of the powertube. The rods are inserted through the clamp to hank the old clamp andthe stub end of the oil electrode on the electrode tube. The contactplate is then disconnected from the clamp and lifted away vertically.The entire supporting mechanism including the carriage then moveshorizontally to clear the space above the electrode receiving tube. Theold clamp and stub electrode can then be removed by a crane. A newelectrode with a clamp attached to its upper end is then inserted in theelectrode receiving tube by means of the crane, and is hung on the upperend of the tube by means of inserted rods. The crane and its cables arethen A trode; and

unfastened and taken away. The carriage is then restored to itsoperating position and the contact plate is fastened to the new clamp bymeans of nuts and bolts. The new electrode is then raised slightly topermit the removal of the temporary supporting rods, and the power tubeis then lowered to bring the cover into place. After the cover isfastened, the furnace is ready to proceed with further steps preliminaryto a melting operation.

Other objects and advantages of the invention will become apparentfrom'the following description and claims, taken together with theaccompanying drawings.

In the drawings:

FIG. 1 is an overall elevational view of a furnace ernbodying theinvention, and showing the parts in full lines in their operatingpositions and in their loading and unloading positions in dotted lines;

FIG. 2 is a side elevational view, on a larger scale, of the electrodefeeding and supporting mechanism shown in FIG. 1;

FIGS. 3 and 4 combined show an elevational view of the furnace takenfrom the left as viewed in FIG. 1;

FIG. 5 is a cross-sectional view of the crucible and related parts;

FIG. 6 is a detailed view showing the crosshead and its related parts,similar to a portion of FIG. 3 but on a larger scale;

FIG. 7 is a detailed view on the same scale as FIG. 6, showing the powertube and its sealing connection through the cover of the electrodereceiving tube;

FIG. 8 is a view on the same scale as FIG. 6, showing in section thelower end of the power tube and its connection to the electrode clamp;

FIG. 9 is a cross-sectional view on line IX-IX of FIG. 6, showing theterminal structure used on the power tube;

FIG. 10 is a View partly in plan and partly in section on the line XX ofFIG. 8, showing the crosshead;

FIG. 11 is a sectional view on the line XI-XI of FIG. 10;

FIG. 12 is a fragmentary section on the line XII-XII of FIG. 2;

FIG. 13 is a plan view of the carriage and related parts of theelectrode supporting mechanism;

FIG. 14 is an elevational view, with certain parts broken away andothers shown in section, of one form of electrode clamp which may beused with the furnace apparatus of the invention;

FIG. 15 is a cross-sectional view taken on the line XV-XV of FIG. 14;

FIG. 16 is a cross-sectional view taken on the line XVIXVI of FIG. 14;

FIG. 17 is an elevational view on a smaller scale of a modified form ofelectrode clamp, showing it resting temporarily on the upper end of theelectrode receiving tube, the latter being shown in section;

FIG. 18 is a cross-sectional view taken on the line XVIII--XVIII of FIG.17;

FIG. 19 is a plan view of an electrode guide structure used inside theelectrode receiving tube;

FIG. 20 is an elevational view of the guide structure of FIG..19;

FIG. 21 is a cross-sectional view of the electrode receiving tube, takenon the line XXI-XXI of FIG. 4, showing the guide structure in place andguiding an elec- FIG. 22 is a view fied form of guide.

Sec. I -General F zirnace Structure- Fl GS. 1 A to 5 These figuresillustrate an electric furnace which is generally indicated by thereference numeral 1. Many details of the furnace structure have beenomitted from FIG. 1 for purposes of clarification. The furnace 1comprises a crucible Z in which an ingot is formed during similar toFIG. 20, showing a modi- -operation of the furnace, a generallycylindrical shell or 4 housing 3 above the crucible 2, and an electrodereceiving casing or tube 4 which projects upwardly from the shell 3. Atruck 9 carries the crucible 2 and is movable between an operatingposition shown in full lines in FIG. 1 and a loading and unloadingposition shown in dotted lines. I

There are three operating levels for the furnace 1. The lowest levelcomprises a crucible chamber 5 in which the crucible 2 and the truck!)are located and in which the crucible 2 and the ingot formed therein areunloaded from the truck 9.

As best seen in FIGS. 1 and 4, the truck 9 carries four jacks 27 whichmay be driven concurrently by means of a motor 28 and suitable gearing,or may be operated individually by means of handwheels 29. The fourjacks 27 support a platform 31, best seen in FIG. 5, comprising a steelbottom plate 31a, an electrically insulating plate 31b, and an upperelectrically conductive plate 310. All three of the plates 31a, 31b, 31chave aligned central openings. The bottom of the crucible 2 rests on theplatform 31. One edge of the plate 310 is provided with an extension onwhich is mounted a plurality of terminals 32 (FIG. 1) of anyconventional construction and ofheavy current carrying capacity. Theterminals 82 are connected by a like plurality of flexible cables 33 toa like plurality of stationary terminals 34 mounted on a busbarstructure 35. The cables 33 are long enough and have sufficient slack sothat the truck 9 may move between its operating position, shown in fulllines in FIG. 1, and its loading and unloading position, shown in dottedlines, without disconnecting either the terminals 32 or the terminals34.

The second operating level of the furnace 1 is the furnace chamber 20.On the floor of this chamber (shown as a steel grating) there is mountedthe furnace shell '5. The shell 3 is of a considerably greater diameterthan the electrode 36 which extends downwardly through that shell, andconsequently provides a substantial annular space around a portion ofthe electrode as best seen in FIG. 5. At the shell 3 variousinstrumentalities having to .do with the control of the atmosphereinside the furnace are connected, as illustrated diagrammatically inFIG. 4. The shell wall is made double to provide a water jacket 3a('FIG. 5) and its top or head is also double walled to provide a headwater jacket 3!).

The electrode tube 4 is mounted on the head of the shell 3 and extendsupwardly therefrom a substantial distance, e.g., 12 to 15 feet. Theelectrode tube 4 is provided to enclose a consumable electrode such asshown as 36 in FIG. 5, which is being fed to the furnace to form aningot 37 in the bottom of the crucible 2.

The electrode 36 may be of compressed titanium sponge as shown andclaimed in detail in the above mentioned copending application of ThomasA. Sindelar, Serial No. 571,810, filed March 15, 1956, entitledConsumable Electrode Billets and Method and Apparatus for Making Same.

It has become conventional in the making of titanium ingots to run thetitanium through a two-step process. In the first step, an electrode ofcompressed titanium sponge, as just described, is formed into an ingothaving a somewhat larger diameter than the original electrode.

.This ingot, which has been considerably purified by the elimination ofthe impurities during its formation, is then passed through a repetitionof the ingot forming step. In this second step, the first ingot is usedas an electrode and is melted down again in an arc and forms removed.The double operation results in an ingot of high purity and homogeneity.Since titanium is still quite an expensive metal, it is commonly usedonly where its peculiar heat resistant properties and high strength toweight ratio are of great advantage. Such properties are at their bestwhen the metal or alloy is most nearly free of undesirable contaminants.Consequently, practically all the present demand for titanium and itsalloys is for the highly purified forms which may best be manufacturedby repeating the melting step.

In any ingot forming operation using consumable electrodes of finitelength, there is left a short butt end of the electrode which may not beused without danger to the clamp structure and possible contamination ofthe ingot. These butt ends are used by welding them to the ends of otherbutts, or other electrode billets. The welding operation commonly usedleaves a groove in the outer surfaces of the electrode, as shown at 36ain FIG. 5.

The ingots formed in the first melt are considerably shorter and moredense than the compressed billets which are supplied to that first melt.In order to provide an electrode of greater length for the second melt,it is common to weld together two or more of the short electrodes fromthe first melt. These electrodes also are characterized by grooves intheir outer surfaces at the weld points, as shown at 36a.

The third or upper level of the furnace 1 has a floor 34 (shown as asteel grid) a short distance (two or three feet) below the upper end ofthe electrode receiving tube 4. This floor supports the electrodefeeding and driving mechanism. That mechanism is all mounted on acarriage 38 which moves horizontally between an operating position shownin full lines in FIG. 1 and a loading and unloading position shown indotted lines in FIG. 1. Mounted on the carriage 38 are two upwardlyextending masts 55 connected at their upper ends by a crossbar 56 (FIG.3). Two lead screws 39 depend from thrust bearings 57 carried by thecrossbar 56. The lead screws 39 turn in nuts 110 which are fixed againstrotation on a crosshead 41. A power tube 42 depends from a thrustbearing 43 on the crosshead 41. Near its upper end, the power tube 42carries a bracket 44 to which are attached a plurality of heavy dutyterminals 45. The terminals 45 are attached to a like plurality of heavyduty flexible electrical cables 46 (FIG. 1), whose opposite ends areattached to fixed terminals 47 located on a busbar structure 48.

The power tube 42 extends downwardly through a sealing mechanism 49(FIG. 3) located on a cover 511 at the top of the electrode receivingtube 4. Below the cover 50, the power tube 42, as best seen in FIG. 5,carries at its lower end a contact plate 51 attached by means of studbolts on which are threaded nuts 52 to an electrode clamp generallydesignated at 53 and described in detail below in connection with FIGS.14 to 16. The electrode clamp 53 engages the upper end of the electrode36 and not. only supports it but serves as a path for con ductingelectricity to it.

Sec. 2.El'ectr0de Supporting Mechanism FIGS. 1 to 13 As mentioned abovein connection with the general furnace structure, the electrodesupporting mechanism is mounted on carriage 38 (FIGS. 1, 2 and 13) whichmoves horizontally between the operating position shown in full lines inFIG. 1 and the loading position shown in dotted lines. The carriage 38comprises a flat steel plate 88 having a recess 88a (FIG. 13) cut in itsfront edge. Four slide bearings 89 depend from the plate 88 and slide ona pair of rails 90. Each rail 90 is mounted on three spaced brackets 91(FIGS. 2 and 3) attached to an I-beam 98, which forms part of thestructure for supporting the floor 34. Underneath each side of the plate88 and on opposite sides of the respective rails 91 there are attachedtwo steel beams 92 (FIG. 3) of channel-shaped crosssection forstifiening the plate '85.

Near the back central portion of the plate 88 there is mounted a bracket93 (FIG. 13) which extends downwardly from the plate 8% and supports areversible motor 94 which drives a traveling nut 95 through suitablegearing. The nut 95 moves along a stationary lead screw '96 attached toa frame member 97 extending between the I-beams 98. By energizing thereversible motor 94, the nut 95 may be driven along the lead screw 96 tomove the carriage 33 between its operating and loading positions.

The two masts 55, shown as steel Lbeams, are mounted on reinforcingplates 99 at the front part of the opposite sides of the plate 88.Vertical reinforcing plates 100 are provided on either side of bothmasts, to stiflen the connection between the masts and the plate 88. Apair of guy members 1191, FIG. 2, are attached at their lower ends tobrackets on the plate 88 and at their upper ends to brackets on themasts 55.

The crossbar 56 connecting the tops of the masts is shown (FIG. 2) ascomprising a pair of channel shaped beams 56a. The two vertical leadscrews 39 are supported on the crossbar 56 by means of combined thrustand guide bearings generally indicated at 57, one of which is shown indetail in FIG. 12. In that figure, the bearing may be seen generally at1112, and includes a tapered outer race 1113 fixed on a plate 1154supported on the crossbar as, a tapered inner race 1115 mounted on theupper end of one of the lead screws 39, and a plurality of balls orother antifriction members 1196, which run between the races. The upperend of the lead screw 39 is provided with a shoulder 39a to receive therace 1115. The race is held against upward movement on the lead screw 39by a pair of jam nuts 107 and a Washer 1118.

The crosshead 41 is supported on the two lead screws 39. The crosshead41 comprises two channel shaped beams 41a held together by means ofbolts 169 (FIG. 10). Adjacent each end of the crosshead 4 1, there ismounted between the two beams 41a a traveling nut structure 116 (seeFIGS. 10 and 11). Each traveling nut structure 1111 comprises two nuts111 which threadedly engage one of the lead screws 39 and which areseparated by a spacer block 112, having an opening at its center toreceive an antifriction sleeve 113 through which the lead screw 39passes. The nuts 111 and the spacer block 112 are held together by meansof a plurality of bolts 114. The spacer block 112 has integrally formedwith it a pair of oppositely projecting trunnions 115 (see FIG. 10)which extend through openings in the respective beams 41a, and whoseouter ends are threaded to receive nuts 116 which bear against bearingplates 117. Each traveling nut structure 110 is thereb} free to pivotfor alignment purposes about a horizontal axis extending through thetrunnions 115. After alignment is completed, the nuts 116 are tightened.

At each end of the crosshead 41 there is mounted a plate 118 whichpivotally supports a pair of flanged rollers 119 adapted to engage theedges of the flanges of the adjacent mast 55. The rollers 119 arehorizontally aligned and engage opposite sides of a mast 55 so as toguide the crosshead vertically and to prevent horizontal twistingmovements of the crosshead.

At its center, the crosshead 41 supports a bearing block 120 by means ofintegral trunnions 121 which project from the opposite sides of theblock 120 through aligned apertures in the beams 41a. The beams 41acarry bearing plates 122 to take the load on the trunnions. The block120 has a vertically extending aperture through its center to receive apin 123 (FIG. 11). An electrically insulating sleeve 123a encircles thepin 123 and insulates it from the block 121 On the lower end of pin 123there is integrally formed a ball 124 (FIG. 6) which is received in aspherical socket formed in a socket base 125 and a cap 126 threaded ontothe base 125. The base 125 is provided on its lower end with aninternally threaded socket 125a to receive the threaded upper end ofpower tube 42. Concentric with the socket 125a, and opening into theupper. end thereof, there is provided a central passage 1251) whichcommunicates with a laterally extending passage 125a adapted to receivean external water supply coupling member 127. Another passage 125d isprovided to receive another coupling member 128 and to providecommunication with the socket 125a. A water pipe 129 is concentric withthe power tube 42 and has its upper end received in the opening 125b.The lower end of the water pipe 129 is provided with a plurality ofwings 1319 which support its lower end above a plug 131 which closes thelower end of the power tube 42. The couplings 127, 128, the variouspassages in the socket base 125 and the water tube 129 cooperate toprovide a path for circulating coolant, e.g., water, from coupling 127through central pipe 129, out through its lower end, up through thepower tube 42 and out the coupling 128. The coolant is necessary becausethe power tube 42 carries heavy electrical currents and tends to becomeoverheated due to the power loss in the resistance of the tube 42.

Just below the socket base 125 there is mounted on the power tube 42 theterminal block generally indicated by the reference numeral 44. Theterminal block 44, as best seen in FIGS. 6 and 9, comprises a pair ofplates 131, a pair of spacer blocks 132, a plurality of bolts 133holding the plates 131 and the blocks 132 together and clamping theassembly on the tube 42. A plurality of cable tip connectors 134 areattached to the ends of t e plates 131 by means of bolts 135. The cabletip connectors 134 are attached to the ends of cables 46 (see FIG. 1).The cables 46 are flexible and have suflicient slack to allow movementof the electrode supporting mechanism between its operating position andits loading and unloading position. This slack is also sufficient toallow the vertical movement of the terminal block 44- between the upperand lower positions shown in FIG. 1.

At an intermediate locality along its vertical length, the power tube 42passes through a seal and joint structure 49 and through an apertureSlla formed in the center of the cover 50 of the electrode tube 4. Theseal and joint structure 49 comprises a socket formed in upper and lowersocket blocks 136, 137, and a ball 138 having a central verticallyextending aperture to receive the power tube 42 and a spherical outersurface which rides in blocks 136, 137. O-ring seals 139 are providedbetween the ball 138 and the power tube 42,.

The lower end of the power tube 42 is threaded into a recess in thecontact plate 51. The power tube 42 and the contact plate 51 are fixedtogether by means of a lock nut 141. Nuts 52 cooperating with stud bolts52w (see FIG. 17) provide for attachment to the contact plate 51 of theelectrode clamp 53 which is described in detail below in connection withFIGS. 14 to 16.

It should be noted that the ball 138 and its cooperating socket,together with the ball 1241 and its cooperating socket allowconsiderable freedom of lateral and angular movement of the powertube-42 relative to the crosshead 41, and vice versa. These jointstructures thereby prevent binding of the various parts during operationof the furnace.

Theelectrode supporting mechanism described above is driven verticallythrough the lead screws 33, which are in turn driven by power actuatingmechanism best illustrated in FIGS. 13 and 2. This mechanism includes amotor 143 connected through a coupling 144 to a speed changingtransmission 145 and thence through a coupling 146 to a right anglespeed reducer 14-7. The output shaft of the speed reducer 147 isconnected through a coupling 148 and a slip friction clutch 149 to amiter gear unit 151 having two output shafts 151 and 152 extending atright angles to each other and connected through suitable couplings toright angle miter gear units 153 and 154 respectively connected to thebottoms. of thelead screws 39.

8 The lower ends of the lead screws 39. extend. through guide bearings155 (FIG. 3) mounted on the masts 55, and are connected to the gearunits 153 and 154 through couplings 1 55a of a conventional type,constructed so that theydo not transfer any thrust to or from the leadscrews 39. I p

The load of the electrode is applied to the lead screws 39 through thecrosshead 41, and the lead screws are supported only at their upper endsby bearings 57. Consequently, the lead screws are stressed only intension, in which condition their strength is greatest;

A tachometer generator 344 is driven from the output shaft of motor 143.A telemetric generator is driven from one of the output shafts of gearunit 151), and is connected to an integrating receiver on the controlpanel to provide the operator with an indication of the position of theelectrode.

Sec. 3.Electr0a'e Changing Operation At the end of a run, the electrodeclamp 53 within the furnace tube '4 will have connected to its lower enda short electrode butt. The operation of removing this butt andreplacing it with a fresh electrode for a new run of the furnace willnow be described.

After the arc current is shut oif at the end of the run, the motor 143is reversed to drive the lead screws 39 in the direction to move thecrosshead 41 upwardly, thereby carrying with its the power tube 12 andthe clamp 53 with the electrode butt attached thereto. The vacuum insidethe furnace is relieved so that it does not tend to hold the cover inplace on the end of the electrode tube 4. When the contact plate 51engages the under side of the cover 511', the cover is lifted from theend of the'electrode tube 4. The upward movement of the electrode buttand its related parts is continueduntil horizontal holes 53a formed inthe electrode clamp 53 are atalevel somewhat above the top of theelectrode tube 4. Rods 156 (FIG. 17) are then inserted through the holes53a. The electrode clamp is rotated by means of rods 156 until they arein line with saddles 157 mounted on the upper end of the electrode tube4 The motor is then driven to move the electrode clamp downwardly untilthe rods 156 rest in the saddles 157. The weight of the electrode buttand the clamp 53 is now taken by the rods 156. The nuts 52 are thenremoved from stud holes 52a. After removal of the nuts 52, the motor 143is again driven to move the power tube '42 and its related partsincluding plate 51 and cover 511 upwardly to the uppermost positionshown in FIG. 1. After these parts reach that position, the motor 143 isstopped and the motor 94 is actuated to move the carriage 38 back to thedotted line position shown in FIG. v1. The clamp 53 is now free overheadfor access by a crane shown diagrammatically at 158, FIG. 1. A ring pin158a (FIG. 17) is inserted in a threaded hole 53b (FIG. 8) formed in theupper surface of the electrode clamp to receive the hook of the crane158. The electrode butt and the clamp are then lifted by the crane 158and taken to another location where the butt may be disassembled fromthe clamp.

A new electrode with a clamp 53 assembled thereon is then moved intoplace by the crane 158, and lowered into the electrode tube 4 until theholes 53a in the clamp are slightly above the saddles 157. The rods 156are then inserted in the holes and are aligned with the saddles,whereupon the crane lowers the clamp until the weight of the electrodeand clamp is taken by the rods 156,

The crane is then unhooked and the ring pin removed from the clamp 53.

The motor 94 is now operated to move the carriage 38 into its operatingposition. When it reaches that position, the motor 143 is run to lowerthe power tube 42 and the contact plate 51 until the latter comes intoengagement with the electrode clamp 53. The nuts 52 are'threaded on thestud bolts 52a to fasten the contact plate 51 to the electrode clamp 53.The motor 143 is then run to lift the electrode slightly and take theweight off the rods 156. The rods are thereupon removed and the motor143 is then run to drive the electrode downwardly until the cover 50again rests on the top of the electrode tube 4. The cover may be clampedin place by means of C-clamps, or any other suitable means. After thefurnace is evacuated, as it is during operation, the difference betweenthe external pressure and the internal pressure tends to hold the cover50 in place so that the C-clamps may then be removed.

Sec. 4.Electrde Clamps. FZGS. 14 to- 18 Two species of electrode clampsare shown in FIGS. 14 to 16 and FIGS. 17 and 18 respectively. Thespecific clamping structures shown herein are described more completelyand claimed in the copending application of Arthur P. Jones and Donald0. Rice, Serial No. 697,702, filed November 20, 1957, now Patent Number2,964,580, issued December 13, 1960.

The clamp of FIGS. 14 to 17 comprises a clamp body 166 which isgenerally T-shaped in vertical cross-section, having a central stemportion and an upper flange portion 1611a. Near its upper end, the stemportion is provided with four grooves 1611b for receiving four pivotpins 161. The pivot pins 161 are held in place in the grooves 1651b bymeans of screws 162. Four clamp arms 163 are attached to the outside ofthe clamp body 160 by means of bolts 16 .1. The lower ends of theseclamp arms tightly engage the sides of the end of an electrode, as bestseen in FIG. 14. The surfaces of the clamp arms facing the electrode maybe variously contoured to accommodate various electrode shapes. Itshould be understood, however, that it is not necessary to have an exactor even a close matching of the clamp arm contours and the electrodecontours. The clamp arms 163 are tightened against the end of theelectrode by means of the bolts 164. The tightening of these boltsaccommodates minor variations in the electrode contour and also tightensthe upper ends of the clamp arms against the pivot pins 161. The upperends of the clamp arms are provided with grooves 163a which arecylindrical in contour, conforming to the pins 161 so that the clamparms can pivot freely on the pins 161 during the tightening of the clamparms against the electrode end.

The clamp 53 of this construction is assembled on the electrode with thelower end of the clamp body 160 abutting against the end of theelectrode, which may have a rough irregular contour. The principal pathof flow of electrical current to the electrode is through the body 160,the pins 161, downwardly through the clamp arms 163 and thence throughthe sides of the electrode. Relatively little current is carried throughthe end of the electrode and the abutting surface of the clamp body 160,since those surfaces are not forced together tightly by the clampmechanism.

The electrical disconnection .and connection of an electrode to the arccircuit may be accomplished during the loading and unloading of thefurnace by the relatively simple mechanism described above in Sec. 3involving the removal and replacement of nuts 52 (FIG. from studs 52a(FIG. 17). The detachment of the electrode furnace from its supportingstructure also serves to disconnect it from the heavy current arecircuit. The operation of attaching the clamp 53 to an electrode may beperformed at a location remote from the furnace, While the furnace isoperating, to prepare the electrode for use in the furnace. The shutdowntime of the furnace between runs is thereby decreased, since it is notnecessary to keep the furnace shut down while a high capacity electricalconnection is made to the electrode structure itself.

FIGS. 17 and 18 show a modified form of electrode clamp generallyindicated by the reference numeral 165. The principal difference betweenthis clamp and the one in FIGS. 14 to 16 is that the electrode body 166is triangular in horizontal cross-section instead of being rectangularas in the case of the body 160. The clamp uses three clamp arms 167instead of the four clamp arms of FIGS. 14 to 16. The three clamp armarrangement is sometimes better for handling electrodes of certaincontours.

FIGS 19 to 22 These figures illustrate two species of electrode guidestructure which is fixed to the inside of the electrode receiving tube4, as shown in FIG. 21. FIGS. 19 to 21 illustrate one species whichcomprises a plurality of spacer rings 16% which .are held in verticallyspaced relationship by a plurality of stretchers 169. The stretchers 169are shown as formed of angle irons and have their angular cornersextending inwardly from the spacer rings 168, as best seen in FIG. 21.The corners of the stretchers 169 fit between the clamp arms 163 (seeFIG. 21), so that when an electrode is lowered into the tube 4, thestretchers 169 prevent rotation of the electrode in the furnace.

FIG. 22 illustrates an alternative and more simply constructed form ofelectrode guide which may be used in place of that shown in FIGS. 19 to21. This electrode guide consists of a steel cylindrical tube 350 havinga plurality of flanges 351 welded to its periphery at spaced pointsalong its length, with two of the flanges near the ends of the tube 356.The end flanges are braced by means of triangular webs 352. A pluralityof holes 350a are located at spaced intervals along the tube 350, tofacilitate handling thereof by means of a crane.

The electrode receiving tube 4 and the guide structure are usuallyoperated at the same potential as the electrode itself, commonly groundpotential. Consequently, it is permissible for these parts to come incontact during operation. On the other hand, the crucible is at adifferent potential (usually positive) from the electrode, and it isdesirable to maintain the lateral spacing between the electrode and thecrucible so as to ensure that the are forms only between the end of theelectrode and the forming ingot. The guide maintains that lateralspacing by holding the ingot against swinging movements. In effect, itserves as an adapter to accommodate differences between the insidediameter of the electrode receiving tube and the outside diameter of theelectrode 36. If an electrode of different outside diameter is to beused, then a guide of different diameter is substituted.

The guide structure of FIGS. 19 to :21 engages the sides of both theclamp and the electrode, while the guide of FIG. 22 engages the clamponly. If the electrode dimensions are oversize, the guide of FIGS. 19 to21 may occasionally bind an electrode. However, the guide of FIG. 22operates satisfactorily even with substantially oversize electrodes.

While I have shown and described a preferred embodiment of my invention,other modifications thereof will readily occur to those skilled in theart and I therefore intend my invention to be limited only by theappended claims.

I claim: 1

1. In an electric furnace, a cover having an aperture therein, socketmeans mounted on the outside of said cover encircling said aperture,said socket means having an aperture therethrough aligned with saidcover aperture, a ball received in said socket means aperture forrotation therein, said ball having an aperture aligned with said coveraperture and said socket means aperture, a power tube connected to anelectrode of said furnace and extending through said aligned aperturesand slidable vertically therethrough, means for effecting verticalmovement of said power tube through said aligned apertures, and slidingseal means within said ball and slidably engaging said power tube, saidball and socket means cooperating to allow limited universal movement ofsaid power tube with respect to said cover.

2. An electric furnace comprising a consumable electrode adapted to befed vertically to said furnace, a clamp Sec. 5 .Electr0de GuideStructures.

,disposed. above and engaging said electrode for holding an upwardlyfacing surface transverse to the vertical, a

contact plate disposed above said clamp and providing a downwardlyfacing surface transverse to the vertical, said surfaces being disposedand formed for mutual engagement upon vertical movement of one towardthe other so as to establish electrical connection of said plate to saidclamp, removable securing means for securing said plate to said clampand with said surfaces in said engagement with each other, meanssupporting said plate for vertical movement thereof and of said clampwhen secured to said plate and for moving said plate vertically .awayfrom said clamp when said securing means is removed, electrical currentsupply means, means electrically connecting said plate to said currentsupply means, and reversible drive means operatively connected to saidplate supporting means for effecting vertical movement of said platesupporting means and of said plate downwardly to .feed said electrode tosaid furnace and upwardly to remove said plate from said furnace.

3. An electric furnace comprising a consumable electrode adapted to befed vertically to said furnace, a clamp disposed above and engaging saidelectrode for holding said electrode for said vertical movement thereofupon vertical movement of said clamp, said clamp providing an upwardlyfacing surface transverse to the vertical, a contact plate disposedabove said clamp and providing a downwardly facing surface transverse tothe vertical, said surfaces being disposed and formed for mutualengagement upon vertical movement of one toward the other so as toestablish electrical connection of said plate to said clamp, removablesecuring means for securing said plate to said clamp and with saidsurfaces in said engagement with each other, means supporting said platefor vertical movement thereof and of said clamp when secured to saidplate and for moving said plate vertically away from said clamp whensaid securing means is removed, electrical current supply means, meanselectrically connecting said plate to said current supply means, acasing defining the space Within said furnace and provided with anupwardly facing opening, temporary support means carried by said casingadjacent said upwardly facing opening thereof, and means removablyengageable with said clamp and adapted to engage said temporary supportmeans for supporting said clamp and said electrode clamped thereby uponsaid temporary support means adjacent said opening of said casing fordetachment and attachment of said contact plate from and to said clampupon removal of said securing means and restoration thereofconcomitantly with vertical movement of said plate. 4. An electricfurnace as defined in claim 2, comprising means defining an electrodereceiving upwardly facing opening in said furnace, and a removable coverfor said opening, said means supporting said plate for vertical movementthereof comprising an electrode supporting member extending slidablythrough an aperturein said cover, sealing means on said cover sealinglyengaging said member, means on the lower end of said supporting memberattaching said contact plate thereto, and means drivingly supporting theupper end of said member for raising and lowering the same.

5. An electric furnace as defined in claim 4, in which said meanselectrically connecting said plate to said current supply meanscomprises terminal means movable with and mounted on said supportingmember above said cover, stationary terminal means, and flexible cablesconnecting said movable terminal means and said stationary terminalmeans.

6. An electric furnace as defined in claim 2, which comprises a carriagemovable between a feeding position above said furnace and a retractedposition spaced horizontally from said feeding position, a frameworkmounted on said said reversible drive means comprising reversible mo-.tor means mounted on said carriage and operatively connected to saidcontact plate supporting means for effecting said vertical movementthereof.

7. An electric furnace, comprising a crucible, an electrode receivingtube extending upwardly from said crucible, a removable cover for theupper end of said receiving tube, means for feeding a consumableelectrode to said crucible including a clamp for engaging a portion ofsaid electrode, removable temporary support means for hanging said clampwith an electrode depending therefrom at the upper end of said tube whenthe cover is removed therefrom, an electrode supporting rod extendingthrough an aperture in said cover, sealing means on said cover sealinglyengaging said rod, a contact plate attached to the lower end of saidrod, demountable means for electrically and supportingly connecting saidcontact plate to said clamp when in position on said temporary supportmeans, means for raising and lowering said rod and operable first tolift said cover and contact plate demounted from said clamp to aposition clear of the receiving tube to permit insertion of an electrodeand its clamp therein to said position on said temporary support means,thereafter to lower the contact plate for attachment to the clamp,thereafter to lift the plate and clamp sufficiently to free thetemporary support means for removal, and thereafter to lower said plateand clamp and the cover into place and then to feed the electrode intothe furnace, and means for supplying electric current to saidvelectrodeincluding said clamp, said contact plate, said rod, terminal meansmounted on said rod, stationary terminal means, and flexible cablesconnecting said rod-mounted terminal means and said stationary terminalmeans. I

8. In an electric furnace, a crucible, an electrode receiving tubeextending upwardly from said crucible, a removable cover for the upperend of said receiving tube, means for vertically feeding a consumableelectrode to said crucible including a clamp for engaging a portion ofsaid electrode, a power tube extending vertically through and movablevertically through an aperture in said cover, sealing means on saidcover sealingly engaging said power tube in said vertical movementthereof, a contact plate attached to the lower end of said power tube,means fastening said clamp to said contact plate for mechanicalsupporting said clamp and said electrode on said power tube for verticalmovement therewith and for electrical connection of said electrode tosaid power tube,

and motor driven means attached to the upper end of the power tube forraising and lowering said power tube.

9. In an electric furnace, a crucible, an electrode receiving tubeextending upwardly from said crucible, a removable cover for the upperend of said receiving tube, means for vertically feeding a consumableelectrode to said crucible including a clamp for engaging a portion .ofsaid electrode, a power tube extending vertically through and movablevertically through'an aperture in said cover, sealing means on saidcover sealingly engaging said power tube in said vertical movementthereof,

a contact plate attached to the lower end of said power tube, meansfastening said clamp to said contact plate for mechanically supportingsaid clamp and said electrode on said power tube for vertical movementthere- .with and for-electrical connection of said electrode to 13limited angular movements of the power tube with respect to thecrosshead and the cover.

11. An electric furnace as defined in claim 10, comprising guide meansin said electrode tube and cooperating with said clamp to limit lateralmovements of the electrode.

12. An electric furnace as defined in claim 9, including a cross-barconnecting the upper ends of said masts, a thrust bearing in saidcross-bar, a lead screw hung from said thrust bearing and extendingdownwardly through said cross-bar, a nut fixed on said cross-head andthreadedly receiving said lead screw, and motor driven means connectedto said lead screw for rotating said lead screw.

13. An electric furnace as defined in claim 12, comprising two suchthrust bearings adjacent opposite ends of the cross-bar, two lead screwsdepending therefrom, two nuts on the crosshead threadedly receiving therespective lead screws, and motor driven means for synchronouslyrotating the two lead screws.

14. An electric furnace comprising a crucible having an upwardly facingopening for receiving therein an electrode moved vertically downwardlythrough said opening into said crucible, an electrode support disposedabove and connected to said electrode to support said electrode, meanssupporting said electrode support for 25 movement thereof transverselyof the vertical between a feeding position above the crucible and aretracted position spaced from the feeding position, guide meanssupported on said supporting means and engaging said electrode supportfor guiding said electrode support to insure vertical movement thereof,motor means, and means operatively connecting said motor means to saidelectrode support for effecting said vertical movement of said electrodesupport to feed said electrode vertically downward into the cruciblewhen said supporting means is in said feeding position and for movingsaid electrode support upwardly with respect to said crucible.

References Cited in the file of this patent UNITED STATES PATENTS1,732,431 Bruggmann Oct. 22, 1929 2,243,096 Hardin May 27, 19412,686,825 Southern Aug. 17, 1954 2,686,826 Paine Aug. 17, 1954 2,789,151Boron et al. Apr. 16, 1957 2,805,270 Boron et al. Sept. 3, v1957 FOREIGNPATENTS 45,286 Norway June 25, 1928 UNITED STATES PATENT. OFFICECERTIFICATE OF CORRECTION Patent No. 3,05%935 October 9,, 1962 Robert J,Garmy It is hereby certified that error appears in the above numberedpatent requiring correction and that the said Letters Patent shouldvreadas corrected below.

Column 12, line 1, for .contact supporting means" read -vcontact platesupporting means Signed and sealed this 2nd day of April 1963.

(SEAL) Attest:

DAVID L. LADD ESTON G, JOHNSON Attesting Officer 7 Commissioner ofPatents UNITED STATES PATENT. OFFICE CERTIFICATE OF CORRECTION PatentN0. 3.057 935 October 9 i 1962 Robert J, Garmy It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent shouldread as corrected below.

for 'fcontact supporting means" read Column 12, line 1, contact platesupporting means ""2,

Signed and sealed this 2nd day of April 1963.

(SEAL) Attest:

ESTON G, JOHNSON DAVID L. LADD Attesting Officer Commissioner of Patents

